Design And Implementation Of Data Acquisition System For Open Parking Lot

In many schools and communities, there are no indoor parking, and instead, open parking lot are used for parking. In an open parking lot, the parking space are dispersed, and planned on the roadside or some other place. Also, there are multiple entries in an open parking lot, so it is hard to use the management methods of indoor parking in open parking lot. It is necessary to design an intelligent management system for open parking lot. We design a scheme that set a data acquisition sensor node on every parking space and use the magnetoresistive sensor to detect whether there is a car in the parking space. The sensor node uploads the data to the management center, the management center process the data to achieve the management of each parking space. The usage of the parking space also can be send to the car networking for public inquiry.This paper design and implement the data acquisition part of the intelligent management system. Include the magnetoresistive sensor node, the central node that used to collect the data of the sensor node and send these data to management center. The magnetoresistive sensor node use HMC5983L magnetoresistive sensor to measure the geomagnetic field and use the geomagnetic field changes to detect the car existence, and use433MHz as the communications channel of the wireless sensor network. The core controlor of the sensor node is a STM8L Single-Chip Microcomputer. For the central node, a STM32microcontroller with RTOS running on it is the core. The RTOS use for multi-task management and coordination. And a GPRS transmitter is used to transmit the parking information to the management center. In order to realize communication between central node and sensor node, design a communication flow based on TDMA scheme. As the sensor node powered by battery, the power control mechanism is introduced to network layer, MAC layer and physical layer of the wireless sensor network. And propose a dynamic transmit power control algorithm based in link quality to achieve power control in physical layer. Finally, the system testing results is present at the end of this paper.Finally, the paper design and implement the data acquisition system. According to the result of actual usage, it shows that the system running as normal, the accuracy of vehicle detection is high and the packet loss rate during parking space information transmitting is low. It has achieved the expected goal of design.